Hi!
Last Sunday I got the info that the firmware update is spread over the air here in Germany. I assume that this also applies to other countries - just try it by checking for updates in the Settings area. The firmware update shows with a text like "MICROSOFTDMG". If the new firmware is not shown, it probably is a matter of days until Microsoft releases it in your area.
The other option is to check for updates with the Microsoft Device Rescue Tool on your PC. Installing updates this way means to reset your phone. But: What you can do before updating this way is to backup your phone - it should be no problem to restore (almost) everything afterwards.
You can see your firmware version by opening Settings - System - Info. Here you find a button like "More info" or so if the version is not shown. The old firmware is version 16082.41014, the new one is 16352.50011.
Have fun!
Heiko